Sara Descarl was a brilliant scientist and surgeon who discovered how to transplant human brains into the bodies of tigers, which then followed her every command, both in her stage act as “Satana, the Tiger Girl” and in her extortion-murder plots.
Satanna started her scientific career as a lab assistant to the brilliant but physically weakening Gerard Shugel. After Shugel's experiments on organ transplants on animals were shut down by the university authorities, Satanna left with Shugel and they eventually came to the Congo where they successfully transplanted Shugel's brain into the body of a massive white gorilla. While initially admiring Shugel's intellect and bravery, Satanna was now sexually attracted to the new Shugel's ferocity and raw power. They parted since, with Satanna perfecting what she had learned from Shugel.
Satanna reappears with an army of anthropomorphic animals, including modified Thanagarian manhawks, and captures Terra while Power Girl fights off the army. This allows the Ultra-Humanite to switch his brain with Terra's and infiltrate Power Girl's life. When Power Girl realized the switch, she retrieved Terra's brain (now in the Ultra-Humanite's previous and weakened gorilla body) from Satanna's base where it was kept for safe keeping, and cuts Satanna's left arm off with her super-vision.